Three-dimensional semiconductor memory device including separation structures and sacrificial layers and electronic system including the same

Abstract

Disclosed are three-dimensional (3D) semiconductor memory devices and electronic system including the same. The 3D semiconductor memory device may include a substrate including first and second regions, a stack structure including interlayer dielectric layers and gate electrodes alternately and repeatedly stacked on the substrate and having a stepwise structure on the second region, a mold structure adjacent to the stack structure on the first region and including interlayer dielectric layers and sacrificial layers alternately and repeatedly stacked on the substrate, a first separation structure crossing the stack structure and extending along a first direction from the first region toward the second region, and a second separation structure crossing the mold structure and extending in the first direction on the first region. A level of a top surface of the first separation structure may be higher than a level of a top surface of the second separation structure.